A NAND flash is a non-volatile memory and is characterized by that data does not disappear after power-off; therefore, the NAND flash is widely used as an external or internal memory. For example, a solid-state disk (SSD) that is increasingly used in a computer system in recent years is implemented based on the flash memory. A solid-state disk may also be called a SSD. The SSD is characterized by a limited number of erasure times, and each read-write operation (may also be call an erasure operation) on the SSD is wear to the SSD to a certain degree; therefore, a lifetime of the SSD is related to a degree of wear. A higher degree of wear indicates a shorter lifetime. Because a bad block may occur due to a programming error or an erasure error when the NAND flash is used for a long period of time, and an increasing number of bad blocks may lead to an increase in the number of read-write times of the NAND flash within the entire SSD, the degree of wear is increased, thereby shortening the service life of the SSD.
At present, in order to meet a requirement of big data storage, it is usually necessary that multiple SSDs form an SSD storage array. If a lifetime of one SSD in the SSD storage array is shortened due to an increase in bad blocks, a lifetime of the SSD storage array is also shortened. That is, the lifetime of the SSD storage array depends on an SSD with a shortest lifetime included in the SSD storage array.